Are you implying that this kind of corruption happens in every single investigation? No one should be prosecuted in cases where it is present, that's for sure.

Are you implying that this kind of corruption happens in every single investigation? No one should be prosecuted in cases where it is present, that's for sure. But I don't see how that leads to the conclusion that "no one should be prosecuted for anything so long as this kind of corruption exists". Plenty of investigations and prosecutions are conducted above board with no corruption to be found.